Modulating B-site atomic environment via Co-doping to meliorate La0.5Sr1.5MnO4 cathode electrocatalysis for protonic ceramic fuel cells

Abstract

Tailoring the B-site atomic environment in K₂NiF₄-type materials offers a strategic approach to optimize electrocatalytic performance. Herein, Co-doping is introduced into the manganite-based La_0.5Sr_1.5MnO_4+δ (LSMO) to generate additional oxygen vacancies and establish Mn⁴⁺/Mn³⁺ and Co⁴⁺/Co³⁺ redox couples, which create efficient electron-hopping pathways and enhance electrocatalytic activity. The resultant La_0.5Sr_1.5Mn_0.8Co_0.2O_4+δ (LSMCO) cathode demonstrates exceptional performance in a protonic ceramic fuel cell (PCFC), delivering a peak power density of 1491 ​mW ​cm⁻² with a low polarization resistance of 0.095 ​Ω ​cm² at 700 ​°C. These metrics significantly surpass those of LSMO-based and Ln₂NiO₄-based cathodes reported in prior studies. The superior performance stems from accelerated oxygen ion migration and enhanced protonation kinetics in LSMCO, as evidenced by electrical conductivity relaxation (ECR) experiments, which promote faster electrode reaction. Coupled with robust durability with minimal degradation, LSMCO emerges as a leading PCFC cathode candidate. This study underscores the effectiveness of Co-doping in reconfiguring the B-site atomic environment of Mn-based K₂NiF₄-related materials, providing critical insights for designing high-performance electrocatalysts. The findings highlight a viable pathway for advancing materials in energy conversion technologies, emphasizing the synergy between tailored atomic environments and optimized redox activity for next-generation fuel cells.